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that reducin a stroke thing was suggested by nandan... all i can say is it can be done.. many racing specs bullets do reduce the stroke to increase power and mainly make bullets rev higher... chk out this website
"uring the 2000 season a plan was hatched to produce an engine to give Ray another ride at the Vintage meetings. We discussed the possibility of building a scaled up Crusader engine to race in the 350 class. Although Royal Enfield did make a larger capacity motor which used the same basic castings, this was a long stroke design sharing the dimensions of the earlier Bullet (70mm Bore x 90mm Stroke). This arrangement was deemed unsuitable for a racing application. After much deliberation, while availability of pistons etc. was investigated, almost "square" measurements of 76mm Bore x 75.5mm Stroke were decided upon, giving an actual capacity of 342.5cc. This will allow for one .020" rebore, while still staying within capacity for races that demand it. For Vintage racing we can rebore to +.060" and still be within the rules. With the basic design criteria laid down, a crankshaft has been constructed from scratch with modified grass track Flywheels into which have been pressed custom made Mainshafts and Crankpin. The Connecting Rod is a steel item. The Big End assembly is caged needle roller bearing and the Piston is from the Hepolite parts book. For initial testing a standard cast iron Cylinder Barrel has been sleeved to the appropriate size and the Crankcase bored out to suit. The Barrel has a large spacer beneath it to stop the piston popping out the top and to allow for compression adjustments. Thanks must at this stage go to fellow vintage racer Ewan Cameron of the infamous Halec clan who has carried out several engineering jobs beyond the scope of Ray's lathe. A Camshaft from Steve Cotrell's box of tuning goodies will tell the Valves what to do, via suitably lengthened, specially made Pushrods. The 250 racing Cylinder Head used at present will probably need further development at a later date to allow it to inhale sufficient quantities of Methanol to produce even more power. After all this, the engine is finally being put together for its first shake down runs at the Mallory Park practice session on March 22nd if everything goes to plan. While Steve is doing that, Ray has yet to finish another set of cycle parts to run it in, as quick changes of engine are not in our game plan. We should have three different Royal Enfield Crusader based machines to use this year, which will keep both rider and tuner fully occupied in the paddock and on the track."
"uring the 2000 season a plan was hatched to produce an engine to give Ray another ride at the Vintage meetings. We discussed the possibility of building a scaled up Crusader engine to race in the 350 class. Although Royal Enfield did make a larger capacity motor which used the same basic castings, this was a long stroke design sharing the dimensions of the earlier Bullet (70mm Bore x 90mm Stroke). This arrangement was deemed unsuitable for a racing application. After much deliberation, while availability of pistons etc. was investigated, almost "square" measurements of 76mm Bore x 75.5mm Stroke were decided upon, giving an actual capacity of 342.5cc. This will allow for one .020" rebore, while still staying within capacity for races that demand it. For Vintage racing we can rebore to +.060" and still be within the rules. With the basic design criteria laid down, a crankshaft has been constructed from scratch with modified grass track Flywheels into which have been pressed custom made Mainshafts and Crankpin. The Connecting Rod is a steel item. The Big End assembly is caged needle roller bearing and the Piston is from the Hepolite parts book. For initial testing a standard cast iron Cylinder Barrel has been sleeved to the appropriate size and the Crankcase bored out to suit. The Barrel has a large spacer beneath it to stop the piston popping out the top and to allow for compression adjustments. Thanks must at this stage go to fellow vintage racer Ewan Cameron of the infamous Halec clan who has carried out several engineering jobs beyond the scope of Ray's lathe. A Camshaft from Steve Cotrell's box of tuning goodies will tell the Valves what to do, via suitably lengthened, specially made Pushrods. The 250 racing Cylinder Head used at present will probably need further development at a later date to allow it to inhale sufficient quantities of Methanol to produce even more power. After all this, the engine is finally being put together for its first shake down runs at the Mallory Park practice session on March 22nd if everything goes to plan. While Steve is doing that, Ray has yet to finish another set of cycle parts to run it in, as quick changes of engine are not in our game plan. We should have three different Royal Enfield Crusader based machines to use this year, which will keep both rider and tuner fully occupied in the paddock and on the track."
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